Technical Teflon tape, pipe dope, or nothing on gas tank drain plug???

I'm reworking the fuel system on Clarence. The gas that's in the tank has been there for several years and smells to high heaven. The gas tank has a drain plug that I'll be removing to drain what's left of the gas out.

When I put the plug back in should I use Teflon tape, pipe dope, or nothing on the plug threads? Having never had the plug out I have no idea what kind of threads it has.

Note: the gas tank is a (then new) Mustang unit that was installed just prior to Clarence being taken off the road for updates about 4 years ago. I can see down through the filler opening and the bottom inside looks shiny just like new. I just want to get the old gas out of there and put in new. When we rebuilt the carb a couple of weeks ago the gas in it smelled also, but that's been taken care of by rebuilding. There is a filter where the gas leaves the tank and also just before entering the carb.

 

Personally I use liquid Teflon tape on things like this, especially if it's going to set atleast a couple days before use.

But that's me.

.

 

For the drain plug I would install teflon tape sparingly ... Although my new Tanks fuel tank plug has nothing.
I assume if it was needed the manufacturer would have provided it.

Just my opinion will be many others along shortly.

 

I use Permatex #2 on a all gasoline fittings.

 

Blue locktite is what I use if anything, comes apart easy enough. Orange loctite for things you dont want or need to come apart often. Generally I dont use anything on the threads of a drain plug though

 

If it’s a NPT you really don’t need anything for it to seal. The enemy is actually over tightening. However I usually use the Teflon liquid type or regular pipe dope sparingly as a lubricant so the fitting doesn’t gall especially if the fitting and hole it goes in are different type metals.

 

Another vote for liquid Teflon pipe dope, it is possible for some of the Teflon tape to break off and cause problems with filters and pumps.

Phil

 

I had to thread some natural gas pipe about 130 feet, unions, etc, when I went to the HW store I was looking over what was there, noticed (and bought) stuff for natural gas fittings. It was yellow in color, not white. For all I know it was so someone could tell it was a gas line, or it had something that withstood natural gas? I dunno, all my pipes still have a yellowish ring at the ends of the joints.

 

This might be helpful. I, too, only use yellow tape on my cars. Never had an issue....

 

The yellow tape seems to be thicker and doesn't shred as easy as the white tap.

Phil

 

If using Teflon tape, just start 1 full thread back from the end of the fitting and you won't get any tape tearing off and ending up in the tank.

Lynn

 

If it's a pipe (tapered) thread a little teflon tape isn't a bad idea. Most tanks use a straight thread and rely on a soft washer or gasket to seal. Nothing additional on those.

 

That’s the key to using tape, ignored by many who gripe about it dislodging.

 

I was under the impression that the yellow tape was designed for natural or propane gas fittings.

 

5 decades ago, when I worked for a natural gas company, we wrapped the yellow tape on wooden stakes marking where the machine was to dig. Made the stakes easier to see. Worked great until the deer ate the tape.

Don't recall any of the service people ever even considering using the tape on fittings.

Jon

 

I never have had a car with anything on the fuel fittings or plugs and no leaks. Lippy

 

That, and wrapping the tape in the correct direction (clockwise looking from the thread end of the bolt, anticlockwise looking from the head of the bolt). Put it on the right way, and tightening the bolts pushes the end of the tape down. Put it on the other way around and tightening the bolt tends to strip up the daggy thread ends.

An old trick slapped into me by an old refrigeration technician many years ago (thanks Greg).

Cheers,
Harv

 

for larger tapered threads (1/4" NPT or larger), I usually use "megatape" from Lowes (nice and thick, only need a few wraps) and for smaller automotive threads like 1/8" NPT or whatever the british pipe thread is, I use permatex thread sealant. either seems to be fine for oil, gas, coolant, diesel or whatever else.

I'm not a plumber, but I think tape/sealant is also important for lubricating the threads so you get a good tight fit without having to struggle with the fittings, and keeps them from seizing up? it's always worked for me, so I don't change. haha

 

You don't need tape or the liquid sealant on the plug to seal it, however, I do use one or the other to help keep the threads from getting rusty. That makes it alot easier getting the plug out years down the road.

 

Hylomar, is made specificly for gas, kinda pricey but it works and does not set up.

 

Okay, tapered threads like a sealer! Tape is good if you wind it right ! Also applying the pipe dope right! It is all about the technique! It’s not rocket surgery!




Bones

 

Been using this for years on pipe thread, especially if both the fittings are steel.....keeps them from rusting together.

 

I prefer the liquid sealers such as the Permatex posted by @1oldtimer.
The Teflon used in this sealer or in tape form is utilized as a thread lubricant and does not have any sealing capabilities on its own.... it is only useful to help you get more turns of the fitting in order to enhance the interference fit that is the real sealing feature of a pipe thread. At low or zero pressure (gravity), NEW (quality) pipe threads seal just fine with no 'enhancements' needed.
IMHO when using tape or liquid, stay at least 2 threads away from the end of the fitting to prevent any of the material going downstream.
Also keep in mind that the use of Teflon can greatly increase the possibility of cracking fittings, housings, etc. from overtightening (the decreased friction of the fit translates to forcing the 'wedge' of the threads together easier than a dry connection).

 

Clean the thread on the wire wheel, a light smear of Permatex no 2 and wind it in till snug. If it still leaks you have a problem. If it hasn't leaked in 20 years don't over think it.

 

I like Permatex aviation sealant. I hate Permatex aviation sealant. See how that works? Seriously tho, it lubes just enuff and seals well with the benefit of never getting too hard to remove later. In all honesty I don't how it would be some 3-4 decades from now, not sure I should care...?

 

NEVER...use Teflon tape. And a plumber showed me why ! Along with helping to figure out peoples fuel and oil feed problems. I've found probably a whole spool of that damned stuff, helping different people find pressure problems, only to find scraps of the tape in where it SHOULDN'T be !!

Teflon paste works well, or I've also use engine oil with VERY good success in the last 40 years !

Mike

 

I use this on my gas tank drain plug. Works just fine.
If it's NPT threads you really don't need anything. This is an aftermarket plastic tank with a nylon pipe thread plug. Will work on steel also.


Seal-All Gas & Oil Resistant High Strength Gas and Oil Resistant Adhesive 2 oz - Ace Hardware

 

I made my first comment about the deer eating the tape "tongue in cheek" so to speak, although the story is totally true.

I personally and professionally will NOT use any form of Teflon on threads; it simply is an answer to a non-existant problem.

I will not attempt to dissuade any from using Teflon, however be aware of the following:

Until the kit business forced me to stop restoring carburetors (time constraint), I restored carburetors for the better part of 5 decades. During that period, I scrapped probably between 200~300 (no, I did not count them) carburetors, many of them factory Rochester tripower carbs, SIMPLY BECAUSE OF TEFLON!

Why?

Teflon is a really good lubricant. Carburetor castings are aluminum or zinc alloy. Especially on factory tripower carbs "the fitting just didn't tighten in the proper alignement with the fuel lines, so I tightened another turn". Yes you did, and you cracked the air horn.

So if you believe in the stuff, great; but PLEASE do not recommend it to a novice without DEMONSTRATING in person HOW YOU use it.

And for those of you who have never used it, please consider the aforementioned caveat BEFORE you do!

Jon

 

Yup, excess here will sodomize the best efforts. Logic and basics should rule the day.

 

I understand the need to not use it on a carburetor, but fluid and air lines that use NPT fittings do need it.